Currently, distribution service such as music distribution to mobile terminal such as smart phone is provided. For example, patent document 1 discloses content delivery system. The content delivery system utilizes IDs (device ID, device authentication ID) including master ID information (unique user ID to identify user, authentication ID for user) and slave ID information (unique information to identify information processing terminals used by an end user of the service; i.e. IP address, domain name, URI (Uniform Resource Identifier), a MAC address, or a serial number) to obtain authentication for the content distribution service. Since the above mentioned content delivery system uses information for identifying user or information processing terminal as the information for authentication, the authentication must be performed on different ID when the user is changed or different information processing terminal is used.